The study will be prospective and multicentred, with 28 participating units in Belgium, France, Switzerland and Sweden. The coordinating centre will be UCL St Luc. The study will start on 1st September 2008 and will aim to include a minimum of 1000 patients. Consecutive patients undergoing elective colorectal resectional surgery for cancer or diverticulitis will be included. In addition to normal preoperative assessment, waist and hip circumference will be measured before surgery and specific data will be collected on intra and post-operative complications and mortality. Data will be recorded using an encrypted, anonymous database using variables carefully selected to assess short and long term outcomes. The study will be the first of its kind to investigate abdominal obesity as a predictive risk factor for colorectal surgery and will also be one of the biggest prospective studies of morbidity after colorectal surgery.